@Serializable(with=MyCustomSerializer::class)

@Test
fun `union type serialization test`() {
    val json = Json { }
    expectThat(json.decodeFromString<Complicated>("""{ "union": true }"""))
        .get { union }
        .isA<Either.Left<Boolean>>()
        .get { left }.isEqualTo(true)

    expectThat(json.decodeFromString<Complicated>("""{ "union": "bob" }"""))
        .get { union }
        .isA<Either.Right<String>>()
        .get { right }.isEqualTo("bob")
}

@Serializable
data class Complicated(@Serializable(with = UnionSerializer::class) val union: Either<Boolean, String>)

class UnionSerializer(val leftSerializer: KSerializer<Boolean> = serializer(), val rightSerializer: KSerializer<String> = serializer()) : KSerializer<Either<Boolean, String>> {
    override fun deserialize(decoder: Decoder): Either<Boolean, String> {

        return either { decoder.decodeSerializableValue(rightSerializer) }.or { decoder.decodeSerializableValue(leftSerializer) }

    }

    override val descriptor: SerialDescriptor
        get() = TODO("Not yet implemented")

    override fun serialize(encoder: Encoder, value: Either<Boolean, String>) {
        TODO("Not yet implemented")
    }

}

fun <R> either(block: () -> R): Either<Exception, R> {
    return try {
        Either.Right(block())
    } catch (x: Exception) {
        Either.Left(x)
    }
}

fun <L, R> Either<Exception, R>.or(block: () -> L) : Either<L, R> {
    return mapLeft { block() }
}